This invention relates to an apparatus for cutting a sheet material such as cloth in the form of a laminate consisting of a number of sheets which are sewed.
An example of a conventional cutting apparatus of this type is as disclosed in the specification of Japanese Patent Publication (KOKOKU) No. 51-12120. The apparatus includes a frame the upper portion of which is provided with an air-permeable bed, and a pressure-reducing chamber provided below the bed. The laminated sheets are placed on the bed and the upper surface thereof is covered with an air-impermeable sheet. A travelling body supported on the frame is reciprocated in the longitudinal direction, a cutter head supported on the travelling body is reciprocated in the transverse direction, and a cutter mounted on the cutter head so as to be movable vertically is turned about a vertical axis. Thus, the laminated sheets may be cut to a desired shape by the cutter.
Another example of such a cutting apparatus is disclosed in the specification of Japanese Patent Publication (KOKOKU) No. 51-19193. This apparatus includes a bottom member interposed between a bed and laminated sheets of a material, a guide member provided on the bottom member, a cutter fitted to the lower end portion of the guide member, and a cutter head. The bottom member is moved longitudinally and transversely in conformity with associated operation of the cutter head, and the guide member is turned in accordance with turning of the cutter.
A number of problems are encountered in these prior-art apparatus. Specifically, in the apparatus disclosed in the specification of Japanese Patent Publication (KOKOKU) No. 51-12120, a cantilever-type configuration is used in the arrangement having the cutter mounted on the cutter head. Consequently, the cutter flexes at cutting owing to resistance offered by the laminated sheet material and bed, as a result of which the laminated sheets cannot be cut in a highly precise manner. With the cutting apparatus disclosed in the specification of Japanese Patent Publication (KOKOKU) No. 51-19193, the cut portion of the laminated sheet material as well as the vicinity thereof is caused to bulge upwardly by the bottom portion. This makes it impossible to cut the laminated sheets with high precision even though the lower end of the cutter is supported by the guide member. In addition, a difference develops between the positions at which the upper layers and lower layers of the laminate are cut; the thicker the laminate, the greater this difference becomes.